Hi Louise,
Not sure what you know about Bond already but I'll give a brief description for others anyway.
Basically there has always been high Duty (Tax) on Whiskey and for a distillery to have to pay this as they produced it would have been prohibitively expensive. So a system was devised where the casked whiskey is kept in Bond. A bonded warehouse is simply a warehouse where goods where duty is payable can be kept securely until they are relased for sale upon which time the duty is paid, but have to be highly regulated and stock carefully recorded and accounted for. These warehouses need to be accessible to custom/revenue personell at all times. This practice quickly transfered over to larger Retail/Supplier outlets. And yes these businesses aged their own whiskey and even blended it.
The beauty of a Bonded warehouse is that whiskey businesses (Distilleries, suppliers, retailers) can stock up on whiskey with out the expense of Duty on top of that and sell as demand requires. It also saves the holder of a full cask of whiskey paying the duty on say of 250 liters of alcohol when they may only yeild circa 80% after 10 years or even only circa 50% after 20+ or more years. Therefore they only paid duty on what they yielded per cask rather than on the entire original cask contents which again would have be a major cost.
How you would reseasrch the history of this in totallium I have no idea but there is still one business I think could be very helpful to you in your quest.
One of the most famous Purveyors of whiskey today due to the longevity of a certain product that you can still access is
Mitchell & sons who were the creators of Iconic whiskey Greenspot. (The brand is now owned by Irish Distillers but is still integral to the Mitchell business)
I am sure they would have no issue talking to you and they would give you a facinating look at how the whole process worked better that I and more as they are very proud of their whiskey credentials.